The present invention relates to wheat gluten, and more specifically to methods of processing wheat gluten products in order to remove components that cause undesirable flavors and color.
Gluten is a mixture of proteins which is present in wheat and, to a lesser extent, in other cereal grains. Gluten is used in making bread because it has an elastic, cohesive nature which permits it to retain carbon dioxide bubbles generated by leavening agents, and therefore to form the framework of the bread.
Wheat flour typically contains about 12% to 13% protein by weight. Gluten represents about 90% of that protein content. The composition of wheat gluten is approximately as follows:
______________________________________ Total protein 80.91% Ether extract 4.20% Fiber 2.02% Ash 2.48% Carbohydrates 9.44% Total 99.05% ______________________________________
The protein component of wheat gluten can be broken down as follows:
______________________________________ Gliadin 39.09% Glutenin 35.07% Globulin (soluble 6.75% in 10% salt solution) Total 80.91% ______________________________________
These three gluten components have different molecular weights. Gliadins and glutenins have average molecular weights of about 40,000 and 300,000 daltons, respectively, while globulin molecular weights range from about 24,000 to 200,000 daltons.
In addition to its well known use in bread, wheat gluten is used or is being considered for use in a number of other food and industrial applications. For example, wheat gluten proteins are a possible substitute for casein, a relatively expensive product derived from milk. This is an especially important potential use, because casein is used in imitation cheese, and the demand for imitation cheese has increased so dramatically in recent years that casein production cannot keep pace.
As another example, opportunities exist for blending wheat gluten proteins with protein isolates and concentrates from glandless cottonseed and soybean flours to make products that are more nutritious than the individual components by themselves. Combining wheat gluten with soy flour protein in a 30/70 weight ratio gives a product with a protein efficiency ratio of 2.4, which is roughly three times the value for wheat gluten alone.
Unfortunately, wheat gluten products made by some manufacturing processes have some undesirable cereal flavors, excess salts, and undesirable color-causing components which present an obstacle to their use in new applications. The components of wheat gluten which cause these properties present an especially difficult problem in food applications. While some processes have been developed for removing undesirable constituents from other protein sources, those processes are not necessarily transferrable to wheat gluten processing because of differences in overall composition. Processes which could increase the utility of wheat gluten would represent a significant advance in helping meet the nutritional needs of the world.